Inhibition of 3-phosphoglycerate dehydrogenase by l-serine.
1. l-Serine was shown to be a highly specific inhibitor of 3-phosphoglycerate dehydrogenase. 2. 3-Phosphoglycerate dehydrogenase is cold-labile with respect to its catalytic activity and to sensitivity to serine. 3. l-Serine protects the catalytic site as well as the inhibitor site. 4. Glycerol protects the catalytic site as well as the inhibitor site. 5. Serine acts as a ;classical' non-competitive inhibitor of fresh preparations of 3-phosphoglycerate dehydrogenase. 6. ;Aged' preparations when assayed at pH6.5 show sigmoid inhibition curves at saturating substrate concentrations. 7. A generalized model is advanced to account for the variation of the catalytic activity and the inhibitory effect of l-serine with time and conditions. 8. The possibility that the sigmoid kinetics of inhibition observed are an artifact of isolation is discussed.
D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors*; D001665:Binding Sites / Q000187:drug effects; D003864:Depression, Chemical; D005990:Glycerol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010944:Plants / Q000201:enzymology; D012694:Serine / Q000494:pharmacology*; D013997:Time Factors
D012694:Serine; D000429:Alcohol Oxidoreductases; D005990:Glycerol